1. Field of the Invention
The present invention relates to a fuel injector for an internal combustion engine and, particularly, to a fuel injector for an internal combustion engine having a slit-like injection hole to produce a spray of a flat fan shape.
2. Description of the Related Art
In a fuel injector for supplying fuel to an internal combustion engine, the injection hole is made slit-like to produce a spray of a flat fan shape. Japanese Unexamined Patent Publication No. 3-78562 discloses such a fuel injector for an internal combustion engine. The spray of a flat fan shape formed by the fuel injected from the slit-like injection hole of this fuel injector has a small dispersion in concentration and a greatly increased surface area of the spray compared with that of ordinary conical spray, enabling nearly all of the fuel to come into sufficient contact with the air and, hence, to be quickly atomized and mixed. This makes it possible to supply, to the internal combustion engine, a fuel spray in which the fuel is sufficiently atomized and which has a small dispersion in concentration.
However, the fuel injector has a problem in that it is difficult to regulate the flow rate of the fuel. The flow rate of the fuel generally is decided by a minimum sectional area of the injection hole. The slit-like injection hole for forming a spray of a flat fan shape has the width which is gradually narrowed inward so that the inside portion of the injection hole has the minimum sectional area. Therefore, when a current flow rate is smaller than the desired flow rate, the inside portion of the injection hole must be machined directly to enlarge the sectional area thereof. This is very difficult.